DelJpegEx

Enhanced Delphi jpeg unit

Now using libjpeg-turbo (based itself on IJG library):
http://www.libjpeg-turbo.org/

Main differences to original unit:
- use libjpeg-turbo; thanks to its optimizations, it's 2-5 times faster!
- reimplemented library source/destination without stdio:
because they are always memory streams, use direct memory access!
-> reduced footprint (library objs), reduced intermediate buffers, faster,
avoid error with "ferror" inside the library
- reduced imports to minimum required
- simple CMYK decoding
- simplified BGR / BGRX conversions (thanks to libjpeg-turbo)
- lossless transformations
- added explicit error strings from the library
- fixed some bugs
- other small fixes